1. Field of the Invention
The present invention relates to a non-invasive method for estimating of the variation of the glucose level ΔG in the blood of a person and to an apparatus for carrying out the method.
2. Description of the Prior Art
At present, a variety of methods and devices for the non-invasive estimation of blood glucose level are known: laser-light scattering and absorption, combinational (Raman) scattering (U.S. Pat. Nos. 7,054,514, 7,454,429, 5,448,992), nuclear magnetic resonance (NMR) methods (U.S. Pat. No. 7,295,006) and impedance spectroscopy (patents US 2002/0155615, RU 2001/115028). The measuring devices based on such technologies have and most likely will still have a high prime cost and hence a high price non-affordable for an individual consumer.
As affordable and thus promising methods for mass consumption, despite of, strictly speaking, indirect character of blood glucose level estimation, impedance or conductometry methods have been considered. Such methods postulate the presence of a connection between the electrical quantities of tissues and the glucose concentration in blood. However, electric parameters of native tissues are directly dependent not only on glucose or other substances maintenance, but also on the condition of their hydration. Despite of all such known physiological mechanisms, there are still no good and reliable non-invasive glucometers working on the basis of a conductivity measurement.